1. Field of the Invention
The present invention generally relates to an electro-hydraulic device for actuating a control element of an internal combustion engine. More particularly, the present invention relates to a system and method for regulating a high-pressure hydraulic supply to electro-hydraulic engine valve actuators.
2. Description of the Background Art
The internal combustion engine is well known and has garnered much attention since its creation. Because of its ubiquitous use, substantial efforts are constantly made to improve designs for the internal combustion engine and for its control systems. Of the many advancements made, independent valve actuation and electronic fuel injection were conceived to improve performance and efficiency over cam-based engines.
With independent valve actuation systems, the engine valves can come in contact with the engine pistons. This valve—piston collision can cause serious engine damage leading to engine failure. Therefore, valve actuation systems are contemplated that prevent such valve-piston collisions from occurring.
Piston-valve collision has been of particular concern for electro-hydraulic valve-trains on non-freewheeling engines, such as heavy-duty diesel engines. The current solution for solving this problem relies heavily on feedback control based upon valve lift measurements, which is neither reliable nor cost effective. For example, U.S. Pat. No. 6,092,495 describes a method of controlling electronically controlled valves to prevent interference between the valves and a piston. While the system can prevent piston-valve collision, it is flawed because a failure in the electrical control system could cause severe engine damages.
Thus, there is a need for new and improved systems and methods for valve control in a combustion engine that provide reliable piston-valve clearance.